Generic antiarrhythmics are not therapeutically equivalent for the treatment of tachyarrhythmias

The consequences of antiarrhythmic drug formulation substitution were asses sed by survey of 130 experts on arrhythmias. Fifty-four arrhythmia recurren ces, 7 proarrhythmic events, and 3 deaths resulting from generic substituti on are reported, thus raising serious concerns about both antiarrhythmic dr ug substitution and the adequacy of the generic drug approval process.